Size comparisons

[DinoFan83]

@"LoveAnimals" 

Quote:From what I have seen from Franoys, Tyrannosaurus is now both larger, taller and heavier than Giganotosaurus.

I do not agree with this. By my estimation, the exact opposite is true; in fact, while I can't say anything on height, we don't seem to have any T. rex specimens that outweigh any known Giganotosaurus specimens.

Quote:Sue is even longer than the largest reliable Giganotosaurus ever found

Disagree, by my linked estimations both above and below the latter is slightly longer (12 vs 12.46 meters). Not to mention, for reasons the link goes over, Sue is quite the poor representative of T. rex size on the whole.

Quote:(not considering the Jaw fragment one since we can never estimate a reliable size)

You may disregard it if you so wish, but the maximally parsimonious assumption favors it to belong to an animal >2000 kg heavier than Sue and >4000 kg heavier than the average T. rex.

Furthermore, a few more things should be noted on Franoys' estimates:

-I have reason to believe the ribcage on their Sue is too wide. It is 1.8 meters (which equals or approaches the width of the very inflated mounted skeleton's ribcage), while other authors have gotten a substantially lower ribcage width when correcting for that. Scott Hartman got about 1.6 meters (even though their Giganotosaurus estimate there is quite incorrect and I can explain why if need be), and Asier Larramendi got 1.5 meters. Correspondingly, their estimates are lower than those from Franoys, and my personal estimate as linked above is lower as well (8200 kg with the revised 0.95 density and 7900 kg with the same density as Franoys').
In summary, I see the lower estimates such as mine as more likely due to that.

-Their Giganotosaurus skeletal does not have the pectoral girdle orientation we see in other allosauroids that preserve an articulated pectoral girdle (eg: Acrocanthosaurus) where the lowest point of the pectoral girdle is roughly equal to the lowest point on the pubis. Instead, it is notably higher up, thus giving the animal a shallower chest than relatives suggest. As you can see in the Giganotosaurus profile thread, the skeletals that have the pectoral girdle and pubis at roughly the same depth suggest a mean estimate of 7850 kg (8320 kg with the new density) for the holotype (as I also said above, this makes the holotype alone a match for Sue masswise).

-Aside from my disagreement with the T. rex and Giganotosaurus estimates explained above, there are a number of estimates in Franoys' predatory dinosaur chart that I have reason to believe are incorrect. They are as follows: 

-Giganotosaurus roseae: From what I can see, Franoys' estimate of 12.2 meters and 6950 kg for the largest specimen is substantially too low. (Before the new density, as the link says these estimates would be even higher with it), the second largest specimen in the bonebed is 13.2 meters and >9700 kg, and the largest specimen is 13.7 meters and 10870 kg by my estimation. Even my estimate of the probable average adult size is >1000 kg larger than Franoys' estimate for the largest.

-Carcharodontosaurus: Franoys' 6400 kg estimation for SGM-DIN 1 appears to be a good deal less likely than SpinoInWonderland's >9000 kg estimate. In fact, as that link says, 9350 kg is a perfectly reasonable size for SGM-DIN 1 when using Franoys' skeletal.

-Spinosaurus: Franoys has yet to update their skeletal for the 2020 paper, and my estimate (that is supported by Nizar Ibrahim) suggests an animal of 10830 kg for the only specimen that can be estimated from overlap at this time.

-Tyrannotitan: There is a lot of stuff about Franoys' 6400 kg estimate that I cannot reconcile with the known remains as well as known allosauroid anatomy. 
First off, Franoys' Tyrannotitan skeletal suffers the same pectoral girdle problem as their Giganotosaurus - it is not level with the pubis as more complete allosauroids suggest. Correcting this brings the estimate to 7000 kg, as per Molina-Pérez and Larramendi (2016). 
That is not everything either - the discrepancy Franoys used between the 2 specimens appears to be too low. They assumed (as per Novas et al. (2005) that the size discrepancy between the 2 specimens was 7% - problem is, there are no written measurements that suggest such a size discrepancy and I don't know how Novas et al. got it. Based on the femoral length discrepancy between the 2 specimens (141 vs 127 cm), we get an animal of 12.2 meters long (coherent with the estimate from Thomas Holtz) and >8000 kg (it would be even more with the new density). Reply